During the construction of vehicles of all types, also, for example, for wind power stations, the requirement for loadable and nevertheless lightweight materials that are as economical as possible is increasing. In particular, fiber composite materials provide an excellent lightweight construction potential. The principle is that, in particular, high-strength and rigid fibers are embedded in a matrix so as to be adapted to the stresses, whereby components with excellent mechanical properties are produced, which are typically 25% lighter than aluminium and 50% lighter than steel structures with comparable performance.
In order to produce fiber composite structures with fibers arranged in accordance with the force flow, so-called preforms have been manufactured as textile semi-finished products for selected applications. These are generally two-dimensional or three-dimensional structures with a fiber orientation designed to be adapted to the stresses.
For example from German Patent Publications DE 100 05 202 B4 or DE 197 26 831 C2, it is known to lay endless thread sheets successively one above the other in their later load directions and to connect them to form a finished preform by a connecting method, such as, for example, sewing in a so-called multi-axial machine.
In a multi-axial machine that has become known from German Patent Publication DE 10 2007 024 124 B3, endless threads are both laid alternately around rows of hooks on transport chains running longitudinally on both sides and also the width of the cut-to-length thread sheets bridging the web of material is temporarily fixed to the transport chains by means of clamping fastenings.
To produce complex preforms, these textile structures are cut to size separately and joined to form thicker packages in a subsequent process, before they are formed into a finished composite component, for example by means of a resin injection process.
In particular, in the case of components, in which curved force flow lines with a varying density are to be expected, it is not possible to produce a corresponding component designed to be adapted to the force flow using the known methods.
A fiber or thread composite has become known from German Patent Publication DE 103 01 646 A1, in which strand pieces are deposited one above the other in a plurality of layers in various depositing patterns and are glued to one another. Although this improves the depositing adapted to the force flow, and the drapeability is improved to a certain extent, this is, however, also not suitable for greater deformations owing to the compact design.
It has therefore been proposed in German Patent Publication DE 10 2007 012 609 A1, to spread rovings apart and to divide them into pieces with a defined length and width, after which these roving pieces are pressed by means of a special laying device with a resiliently deformable surface flat onto a three-dimensional forming area. These roving pieces are fixed by means of a binder material on the three-dimensional forming area. The distribution of the roving pieces on the three-dimensional forming area takes place in such a way that these are placed and fixed at predefined positions. When using a thermally activatable binder, it has proven to be advantageous to attach a heating device to the laying head and to heat the fiber band piece during transportation to the depositing site, whereby the binder is activated.
As an alternative to this type of thermal fixing, it is described in Great Britain Patent Publication GB 2 268 699 A, that a plate that is spatially deformable by a large number of adjustable supports can be used as a tool for shaping plastic material webs, the heating device being integrated in the tool to fix the spatial shape.
Compared to the remaining prior art, a substantially better adaptation of the stretching of the rovings in the direction of the force flow lines in the fiber composite structure is achieved by the invention of German Patent Publication DE 10 2007 012 609 A1. However, it is disadvantageous that a very complex laying device with a plurality of degrees of freedom is necessary for the depositing adapted in each case to the respective three-dimensional forming area, of the roving pieces. A laying device of this type is not only very expensive because of its complexity, but also very laborious to program and extremely limited with respect to productivity. It is therefore suitable, in particular, for complicated structures and small piece numbers. In the case of larger piece numbers and larger areas, a device of this type cannot be used.